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<html lang="en">
<head>
    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <!--* 反转字符串
       var str = 'abcdefg'
       
       // 要求结果
       // gfedcba  -->
    <script>
        var str = 'abcdefg';
        var newstr = str.split("").reverse().join("");
        
        console.log(newstr);
    </script>
</body>
</html>